1. Field of the Invention
The present invention relates to an ink jet recording apparatus for performing recording by discharging ink onto a recording material from recording means, and more particularly, to an ink jet recording apparatus which enables improved recovery.
2. Description of Related Art
A recording apparatus functioning as a printer, a copying machine, a facsimile machine or an output device for a composite machine containing a computer, a word processor or a work station, is designed to record images (including characters and symbols) on a recording material (a recording medium), such as paper or a thin plastic projector film, on the basis of image information. In recent years, ink jet recording apparatuses have been drawing attention and have come into wide use.
An ink jet recording apparatus performs recording by discharging ink onto a recording material from recording means (a recording head), and is advantageous in that the apparatus can be readily made compact, high-definition images can be recorded at a high speed, recording can be done on normal paper without special processing, running cost is low, the noise level is low because the apparatus uses non-impact recording, and color images can be readily recorded using inks of many colors.
Ink jet recording means (a recording head) for discharging ink by utilizing thermal energy is made up of electrothermal transducers and electrodes formed on a substrate (by semiconductor manufacturing processes, including etching, deposition and sputtering), liquid passage walls and a ceiling. Thus, an ink jet recording means in which the liquid passages (discharge ports) are disposed at a high density and which is thus more compact, can be readily manufactured. Further, an ink jet recording means can be readily made long or two-dimensional by utilizing integrated circuit technologies and micro-processing technologies, thus facilitating the provision of fully multiple or highly complex recording means.
When conducting recording with an ink jet recording apparatus, foreign matter, such as ink, dust or powder, may attach to the discharge port surface of a recording head (an ink jet head). In order to remove such foreign matter, wiping means is used, constructed to clean the discharge port surface by rubbing the surface with a blade made of a rubber-like elastic member, such as urethane rubber.
Conventionally, the surface of the recording head on which ink discharge ports are arrayed is flat. Thus, a cleaning blade having an edge shape corresponding to that flat surface has been used to clean the above recording head. Further, a cap member for protecting the discharge ports can be tightly fitted to the flat surface.
In recent years, recording heads in which a shoulder is formed on the discharge port surface thereof, shown in FIG. 1, have been proposed aimed for facilitating manufacturing and improving ink dischargeability.
FIG. 1 illustrates cleaning conducted on the recording head having such a discharge port surface using a conventional cleaning blade.
In FIG. 1, a blade 90 is moved along the axis on which discharge ports formed in a discharge port surface 91 are arrayed, i.e., perpendicular to the plane of the figure, so as to clean the discharge port surface 91. A first parallel surface portion 93 and a second parallel surface portion 94 are formed on a front surface of a recording head 92 (a head cartridge) on the right and left as viewed in FIG. 1, respectively, in such a manner that they form therebetween a shoulder having a predetermined height. The shoulder portion between the first and second parallel surface portions 93 and 94 is inclined to form an inclined surface portion which is the discharge port surface 91. The blade 90 is disposed such that the distal end thereof is parallel to the first and second parallel surface portions 93 and 94. The distal end portion of the blade 90 has a width W which is sufficiently larger than the width of the inclined surface portion 91, as shown in FIG. 1, and is disposed such that two edges thereof are within the first and second parallel surface portions 93 and 94, respectively.
In the ink jet recording apparatus, capping of the discharge port surface is performed during non-recording in order to prevent drying of ink near the discharge ports and to protect the discharge port surface. Conventionally, this capping is performed by pressing a cap, made of a rubber-like elastic member and provided on an apparatus body, against the discharge port surface, even if the discharge port surface is formed of the inclined surface portion 91.
However, in the ink jet recording apparatus with a head having such a discharge port surface, wiping such an inclined discharge port surface by the blade had the following disadvantages. First, since one edge of the distal end portion of the blade 90 extends to the first parallel surface portion 93 of the recording head 92, as shown in FIG. 1, the blade 90 cannot be brought into contact with the recording head uniformly, precluding the distal end of the blade 90 from making complete contact near the discharge ports of the inclined surface portion 91. Second, the contact pressure of the blade 90 against the inclined surface portion 91 (the discharge port surface) is irregular, generating stripes of wiped and non-wiped regions on the inclined surface portion 91. Third, excess ink is generated near the boundary between the discharge port surface 91 and the first parallel surface portion 93, scattering ink when the blade 90 is separated from the recording head 92. Fourth, the wiping conditions vary due to variations in the position of the recording head 92.
The conventional capping operation performed by pressing the rubber-like elastic cap, provided on the apparatus proper, against the discharge port surface formed by the inclined surface portion has the following disadvantages. First, since the discharge port surface is not a single flat surface but has a small inclined surface portion 91, when capping is performed at a predetermined position, ink leakage may occur due to positional deviation of the cap or due to deterioration in the accuracy with which the carriage with the recording head mounted thereon is moved. Second, since the cap provided on the apparatus proper is made of a rubber-like elastic member, the material may deteriorate with time through contact with the ink. Third, in order to eliminate the above-described ink leakage or deterioration in the material, an equalizing mechanism for bringing the cap into contact with and separating it from the discharge port surface must be provided. The equalizing mechanism has a complicated structure, is expensive and often malfunctions, making handling of the apparatus troublesome. Fourth, since there is no member for protecting the discharge port surface, the ink may flow out of the discharge port surface, or the discharge port surface may contact and be damaged by a bent or wrinkled sheet of recording paper.